// Copyright 2019 Google LLC
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
//      http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.

package cryptofmt_test

import (
	"testing"

	"github.com/google/tink/go/core/cryptofmt"
	tinkpb "github.com/google/tink/go/proto/tink_go_proto"
)

var tests = []struct {
	keyID  uint32
	result string // expected prefix
}{
	{
		keyID:  1000000,
		result: string([]byte{0, 15, 66, 64}),
	},
	{
		keyID:  4294967295,
		result: string([]byte{255, 255, 255, 255}),
	},
	{
		keyID:  0,
		result: string([]byte{0, 0, 0, 0}),
	},
}

func TestOutputPrefix(t *testing.T) {
	key := new(tinkpb.Keyset_Key)
	for i, test := range tests {
		key.KeyId = test.keyID
		// legacy type
		key.OutputPrefixType = tinkpb.OutputPrefixType_LEGACY
		prefix, err := cryptofmt.OutputPrefix(key)
		if err != nil || !validatePrefix(prefix, cryptofmt.LegacyStartByte, test.result) {
			t.Errorf("incorrect legacy prefix in test %d", i)
		}
		// crunchy type
		key.OutputPrefixType = tinkpb.OutputPrefixType_CRUNCHY
		prefix, err = cryptofmt.OutputPrefix(key)
		if err != nil || !validatePrefix(prefix, cryptofmt.LegacyStartByte, test.result) {
			t.Errorf("incorrect legacy prefix in test %d", i)
		}
		// tink type
		key.OutputPrefixType = tinkpb.OutputPrefixType_TINK
		prefix, err = cryptofmt.OutputPrefix(key)
		if err != nil || !validatePrefix(prefix, cryptofmt.TinkStartByte, test.result) {
			t.Errorf("incorrect tink prefix in test %d", i)
		}
		// raw type
		key.OutputPrefixType = tinkpb.OutputPrefixType_RAW
		prefix, err = cryptofmt.OutputPrefix(key)
		if err != nil || prefix != cryptofmt.RawPrefix {
			t.Errorf("incorrect raw prefix in test %d", i)
		}
	}
	// unknown prefix type
	key.OutputPrefixType = tinkpb.OutputPrefixType_UNKNOWN_PREFIX
	if _, err := cryptofmt.OutputPrefix(key); err == nil {
		t.Errorf("expect an error when prefix type is unknown")
	}
}

func validatePrefix(prefix string, startByte byte, key string) bool {
	if prefix[0] != startByte {
		return false
	}
	return prefix[1:] == key
}
